Accelerometer Bonding Member Design for Thermal Expansion Distortion
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Solution Overview
Problem
Conventional accelerometers with dissimilar materials for substrates and support members experience performance degradation due to thermal expansion differences, leading to bias and drift in output values.
Innovation Solution
A sensor design with a bonding member strategically placed between the substrate and support member, reducing the bonding area to minimize thermal expansion distortion, and using a pedestal with an adhesion layer to stabilize the bonding interface, ensuring equal thermal expansion coefficients and reduced stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the substrate and support member are bonded over the entire substrate surface, then the bonding strength is improved, but thermal expansion distortion is transmitted to the sensor elements causing performance degradation
Solution Approach 1:
The bonding member is divided into a pedestal portion and an adhesion layer portion, with the adhesion layer segmented into first and second regions that straddle the sensor elements. This segmentation allows the bonding interface to be distributed in a way that balances bonding strength with minimization of thermal expansion distortion transmission to the sensor elements.
Solution Approach 2:
The adhesion layer is configured with different regions (first and second regions) that have different spatial relationships to the sensor elements. The first region is arranged closer to the first sensor element while the second region is arranged closer to the second sensor element, creating local quality variations that compensate for thermal expansion distortions at different locations.
2Stability of the object's composition
If dissimilar materials with different coefficients of thermal expansion are bonded together, then the structural stability is improved, but thermal expansion distortion is generated causing bias and drift in output values
Solution Approach 1:
The bonding member acts as an intermediary between the substrate and support member, with its pedestal portion providing mechanical support and its adhesion layer providing bonding while minimizing thermal expansion distortion transmission. This intermediary structure mediates the interaction between dissimilar materials to prevent distortion from reaching the sensor elements.
Solution Approach 2:
The adhesion layer is configured asymmetrically with respect to the sensor elements, with the first region arranged closer to the first sensor element and the second region arranged closer to the second sensor element. This asymmetric arrangement creates compensating effects that cancel out thermal expansion distortions in the differential output.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces performance degradation by canceling out thermal expansion distortions between sensor elements and maintaining accurate differential value output, enhancing detection accuracy and reliability.
Implementation Method 1
dissimilar materials (the substrate and the support member) having coefficients of thermal expansion different from each other are bonded to each other, and hence a variation (such as a bias or drift) is generated in the output value of the accelerometer due to distortion transmitted from one side (support member) to the other side (substrate)
Implementation Method 2
a pedestal and an adhesion layer arranged on a surface of the pedestal
Data Source
AI summary
This accelerometer (100) includes a substrate (30) and a bonding member (90) that bonds the substrate (30) and a supporting member (50) to each other, and the bonding member (90) is arranged in a region (R3) that straddles a first region (R1) in which a first sensor element (11) is arranged and a second region (R2) in which a second sensor element (12) is arranged in a plan view.